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'Candidatus Phytoplasma prunorum' - a pathogen spreading uncontrollably in apricot orchards in the Czech Republic

Necas, T., Ondrasek, I., Krska, B.
Acta horticulturae 2015 no.1105 pp. 131-136
Phytoplasma, apricots, biotic factors, cultivars, fungi, leaves, monitoring, mortality, orchards, pathogens, phytoplasmal diseases, tree mortality, trees, Czech Republic
Tree mortality of apricots involves many abiotic and biotic factors. The most important biotic factors include bacterial, fungal and viral diseases and especially phytoplasmas. Generally it is very difficult to determine the primary pathogen causing premature mortality in trees of apricot. However, according to long-term monitoring of apricot orchards in the Czech Republic (South Moravian region), the ESFY phytoplasma, 'Candidatus Phytoplasma prunorum', in infected orchards induced low production and caused up to 30% annual mortality of trees (in young trees up to 40% mortality). The main symptom that points to the presence of phytoplasma in infected orchards is chlorotic leaf-roll occurring in 45% of cases of infected trees. Among the other symptoms are typically leaf yellowing or leaf-roll and premature leaf fall. Other symptoms are often cultivar specific. In the evaluated orchards, sensitive cultivars included 'Hargrand', 'Bergarouge', 'Bergeron', 'Pinkcot', 'Silvercot', and especially 'Aurora'. The least affected cultivars included 'Goldrich' and 'Orangered'. Based on field ratings, the cultivar 'Poyer', had a higher tolerance to phytoplasma ESFY.